MMC SD fs boot partition config coding style and proper description

CONFIG_SYS_MMC_SD_FS_BOOT_PARTITION ought to be called
CONFIG_SYS_MMCSD_FS_BOOT_PARTITION to keep it consistent with other config
options such as: CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR.

In addition, it is not related to raw mode booting but to fs mode instead.

Signed-off-by: Paul Kocialkowski <contact@paulk.fr>
Reviewed-by: Tom Rini <trini@ti.com>
diff --git a/include/configs/mcx.h b/include/configs/mcx.h
index b775ebd..26eb220 100644
--- a/include/configs/mcx.h
+++ b/include/configs/mcx.h
@@ -369,7 +369,7 @@
 #define CONFIG_SPL_BSS_MAX_SIZE		0x80000
 
 #define CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR	0x300 /* address 0x60000 */
-#define CONFIG_SYS_MMC_SD_FS_BOOT_PARTITION	1
+#define CONFIG_SYS_MMCSD_FS_BOOT_PARTITION	1
 #define CONFIG_SPL_FS_LOAD_PAYLOAD_NAME	"u-boot.img"
 
 /* NAND boot config */